Method of dephosphorizing metal by the bessemer process



' passes into the slag or basic bath which covers the metal, as silicic acid or a silicate of of the method and a more intelligent use of the UNITED STATES PATENT FFICE.

JACOB REESE, OF PITTSBURG, ASSIGNOR TO THE BESSEMER STEEL COM- PANY, (LIM'ITEDQ OF PHILADELPHIA, PENNSYLVANIA.

METHOD OF DEPHOSPHORIZING METAL BY THE BESSEMER PROCESS.

SPECIFICATION forming part of Letters Patent No. 278,788, datedJ'une 5, 1883.

Application filed July 28, 1879.

To all whom, it may concern: I

Be it known that I, J ACOB REEsE, of the city of Pittsburg, county of Allegheny, State of Pennsylvania, have invented a new and useful Method of Dephosphorizing Metal by the Bessemer Process, of which I declare the following to be a full, clear, and exact description.

In order that the invention and its advantages, hereinafter described, may be the more fully understood, reference will first be had to the state of the art previous to this invention.

On the 11th day of September, 1866, Letters Patent were granted to me for an improved process of reducing, dephosphorizing, and refining metals, and for machinery adapted to the production of the results claimed. In the body of that specification is set forth the important fact that the reducer or converter should be lined with such material as will resist the heat and chemical action of reducing and refining, which may be varied according to the chemical composition of the material under treatment. Thus, if the iron or ore contains little or no silica or alumina, pure lime, or oxide of calcium, may be used for lining the reducing-chamber. 7

The invention which I am now about to describe, and which forms the subject-matter of this specification, consists in an improvement agents employed for producing dephosphorized steel as set forth in said Letters Patent No. 57,969.

It is awell-known fact in the metallurgy of iron that the phosphorus cannot be dispelled from the metal while silicon is incorporated with it in any considerable degree, or while it is present to any great extent in the lining of the metal chamber or the bath which covers the metal. Therefore, to secure a thorough dephosphorization of iron and steel, the furnace or chamber should be constructed or lined with material as free from silicon as possible, as the presence of silicon prevents the chemical action requisite to eliminate phosphorus. All the silicon contained in the metal under treat ment must be burned out before dephosphorization takes place. The silicon thus burned iron, and is liable to again be taken up by the iron. Therefore it is desirable to, have metals low in silicon and a furnace and bath free from silica. In order to secure these results, I line my metal chamber with a lime lining and cover the metal with a basic bath as free from silica as possible, and by these agents, when metals low in silicon are worked, a complete dephosphorization takes place; but in practice it is found desirable in the Bessemer process to have metals containing at least two per cent. of silt con for the purpose of developing the necessary amount of caloric to keep the metal fluid during the operation. arises, not only to the dephosphorization of the metal, but, the slag becoming silicious, it is very destructive to the lime lining of the vessel, which causes considerable expense and retards the working of the plant by repairs. Now, to obviate these difficulties and to secure all the advantages of the Bessemer process in dephosphorizingall grades of metal, whether high or low in silicon, I have invented and now desire' to secure Letters Patent for the process which Ishall now describe clearly, so that those skilled in the art may use the same.

In the operation of this process I employ the ordinary Bessemer plant with the addition of an auxiliary converter, the ordinary converter being lined with ganister and the auxiliary converter being lined with lime. The lime lining may be in the form of magnesian limestone or in the shape of bricks principally of lime; or magnesian burnt lime may be admixed with petroleum and rammed in while in a plastic condition. I prefer the latter, as in practice I have found it to be the most easily applied and most desirable.

The operation of the process is as follows: The converter being properly heated, the mo1 ten metal is caused to flow into the converter containing the ganister lining, and, the vessel .being turned up, a blast of atmospheric air is forced through it. The oxygen of the air ox- Thus the difficulty idizes the carbon contained in the metal, which in a finely-divided state through the metal by means of the blast. This stage of the process will not require more than from three to five minutes, according to the amount of phos phorus contained in the metal. After the dephosphorization'has been thoroughly effected,

which may be determined by the color of the flame, the converter is turned over on its side and a proper amount of manganesic carbide of iron is run into the metal, the manganese devouring the oxide remaining in the metal, the carbon recarburizing it to the desired degree. This addition causes a lively ebullition of the metal. lVhen the ebullition has ceased, the metal is poured out into suitable molds and the slag emptied out on the ground, and the operation continued on another batch of metal.

Great care should be taken in emptying the desiliconized metal from the ganister converter into the converter lined with lime that no slag be allowed to pass into it, as the slag is highly silicious, and will not only retard the dephosphorization of the meta-1, but will also be destructive to the lime lining.

The advantages of this invention are, first, the manufacture of high grades of Bessemer steel fi'om metals high in silicon and phos- Some of the iron also be-- phorus; second, securing the perfect dephosphorization 1 of the metal by desiliconizing it and then removing it from the silicious lining and slag to a non-silicious vessel, in which it is dephosphorized and carburized. The third advantage is in securing the desirable chemical conditions of desiliconizing the metal in a silicious-lined vessel and dephosphorizing it in a calcareous-lined vessel, as lime is not only destructive to the silicious or ganister lining, but silicon is also destructive to a lime lining.

I do not claim the use of a lime lining, as I have already received a patent therefor. N or do I claim injecting oxide of iron into the metal by means of the blast, because I have obtained Letters Patent therefor. Nor do I new claim injecting lime into the metal by means of the blast, as I have lately applied for Letters Patent forthe same. Neither do I claim decal-burizing and desiliconizing metal in a converter and then conveying the metal into an open hearth for dephosphorizing and further refining it by the use of other fuel than that 0011- tained in the metal, as I have applied for Letters Patent for the same.

\Vhat I do claim as my invention, and wish to secure Letters Patent for, is

The process of dephosphorizing metal, c011- sisting in first desiliconizing the metal in a silicious or ordinary lined converter, and subsequently removing the metal to and treating it in a calcareous-lined converter, substantially as specified.

JACOB REESE.

itnesses:

GEORGE O. REEsE, FRANK M. REEsn. 

